Browsing by Subject "Grooved wick"

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Open Access
Effect of design and operating parameters on the thermal performance of aluminum flat grooved heat pipes
(Elsevier, 2018-03-05) Alijani, Hossein; Çetin, Barbaros; Akkuş, Y.; Dursunkaya, Z.
Four aluminum flat grooved heat pipes with groove widths of 0.2, 0.4, 0.8 and 1:6 mm are fabricated and the effect of filling ratio on the thermal performance is experimentally studied for four different heat flux values of 2.1, 3.2, 4.2 and 5:3W=cm2. An optimum filling ratio corresponding to each heat flux is determined where the heat pipe has the best thermal performance. Thermal performance of the heat pipes are evaluated using three indicators; (i) the temperature difference between the heat source and heat sink surfaces, (ii) the temperature difference between the peak system temperature and the temperature of the cooling ambient and (iii) heat pipe effectiveness defined as a temperature difference ratio under dry and operating conditions. A flow and evaporative mass scaling model is developed to interpret the experimental findings. Experimental results reveal that at the optimum point the heat pipe with the 0:4 mm groove width has the best thermal performance, and the heat pipe with the smallest 0:2 mm groove operates under dryout conditions even for the lowest heat flux, the reason of which is discussed based on interpretation of underlying phase change physics. Experiments reveal the existence of two operating regimes; with and without dryout in the grooves. Although higher heat loads can be carried under dryout conditions, a limit exists for the maximum heat flux where the pipe operates without the onset of dryout for a specific groove density.
Open Access
Performance assessment of commercial heat pipes with sintered and grooved wicks under natural convection
(TIBTD, 2019) Atay, Atakan; Sarıarslan, Büşra; Kuşçu, Yiğit F.; Saygan, S.; Akkuş, Y.; Gürer, A. T.; Çetin, Barbaros; Dursunkaya, Z.
Heat pipes are widely used in thermal management of high heat flux devices due to their ability of removing high heat loads with small temperature differences. While the thermal conductivity of standard metal coolers is approximately 100–500 W/m.K, effective thermal conductivities of heat pipes, which utilize phase-change heat transfer, can reach up to 50,000 W/m.K. In industrial applications, commercially available heat pipes are commonly preferred by thermal engineers due to their low cost and versatility. Thermal performance of a heat pipe is functions of heat pipe type and operating conditions. Selection of the appropriate heat pipe complying with the operating conditions is critical in obtaining satisfactory thermal management. One key point for the utilization of heat pipes is to avoid dryout operation condition in which heat pipes operate no more at the desired heat transport capacity. In the current study, the performance of cylindrical heat pipes with sintered and grooved wick structures, which are among the most commonly used types, is experimentally tested at different heat loads, gravitational orientations and ambient temperatures. Dryout limits of the heat pipes are determined and the relationship between the dryout onset and operating conditions is elucidated. The results reported in the present study are expected to guide thermal engineers for the proper selection and operation of conventional heat pipes.